Experts and BHG readers answer.
Get Green tomatoes on plant to turn red sooner
Thanks for writing. I don't know of anything you can do to naturally ripen tomatoes faster; the fruits just have to mature on their own. The fruits need a certain amount of heat to ripen, so they'll be slower in cool summers and faster in warm summers.
That said, I've heard some gardeners keep their tomatoes on the dry side to help encourage them to go red faster. I've not had the opportunity to try this, so I can't say whether it works. It may be worth a try --- though watch out because it may cause other problems (such as blossom drop).
Lastly, watch the varieties you're growing. Select types bred for cool, shorter summers if that's what your area experiences. They'll be better adapated to your area that way.
---Justin, Senior Garden Editor, BHG.com